1. Field of the Invention
The present disclosure relates to blade assemblies, and more particularly to air seal systems for a rotor blade assembly of a gas turbine engine, for example.
2. Description of Related Art
Air seals are formed between various components of gas turbine engines, such as between rotating turbine blades and the inner surface of a turbine casing. In this regard, some air seals are provided as an abradable air seal that incorporates an abradable material affixed to the inner surface of the casing. The abradable material is contacted and abraded by the rotating blade tips of the turbine blades during operation.
Other air seals are provided as wear resistant seals. Wear resistant seals also employ materials affixed to the inner surface of the casing. Such materials, however, are selected for erosion resistance, oxidation resistance and/or thermal protection, for example.
Selection of materials for forming such an air seal typically involves a compromise between resistance to wear by erosion, abradability by blade tips, spallation resistance and environment durability. Exemplary materials are set forth in U.S. Pat. No. 4,936,745 and U.S. Pat. No. 5,780,171, which are incorporated by reference herein in their entireties. Additionally, each of U.S. Pat. Nos. 6,284,323; 7,662,489; 8,343,587; 8,506,243; 8,535,783; and U.S. Patent Application Publication Nos. 2008/0138658 and 2010/0098865 is incorporated by reference herein in its entirety. Notably, materials with higher abradability tend to suffer from excess erosion, while less abradable materials tend to be susceptible to spallation. Erosion, spallation, and the like can reduce a seal's effectiveness, which can have a negative impact on thrust specific fuel consumption (TSFC).
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for air seal systems that allow for improved lifetime thrust specific fuel consumption. There also remains a need in the art for such systems that are easy to make and use. The present disclosure provides a solution for these problems.